DETROIT (AP) -- An untimely bobble by Dustin Pedroia and a pair of four-pitch walks from Jake Peavy cost the Boston Red Sox a chance to take control of the AL championship series.

Detroit scored five runs off Peavy in the pivotal second after Pedroia fumbled away his opportunity at an inning-ending double play, and the Tigers beat Boston 7-3 Wednesday night to tie the best-of-seven playoff at two games apiece.

Peavy picked a bad time to have his worst performance of the year. Acquired in late July as part of a three-team trade that included the Tigers, the right-hander allowed a season-high seven runs in three-plus innings.

He didn't get much help from Pedroia during Detroit's big rally.

Boston's normally sure-handed second baseman booted a sharply hit grounder that could have been converted into a critical double play. Instead of holding the Tigers to one run in the inning, the Red Sox had to settle for a force at second and Detroit took advantage by scoring four more runs.

"He's so consistent. He's such a good defender," Red Sox manager John Farrell said. "He squares it up and typically that's a routine double play we've seen many, many times over. Like I said, it handcuffed him a little bit, just enough to not be able to turn a double play."

Peavy gave up five hits in his shortest start since June 4, when he was still with the Chicago White Sox. The Tigers helped Boston acquire Peavy in a three-team deal less than three months ago that netted Detroit rookie shortstop Jose Iglesias.

Victor Martinez hit a leadoff single in the second off Peavy, making his first appearance in a league championship series game. Peavy walked Jhonny Peralta on four pitches and gave Alex Avila a free pass in an eight-pitch at-bat to load the bases.

After getting Omar Infante to pop up, Peavy walked in the game's first run when he failed to throw one strike to a slumping hitter.

Austin Jackson, who entered batting .091 in the postseason, didn't have to swing during a four-pitch walk that made it 1-0. It was just the second time in Peavy's 13-year career that he gave up a pair four-pitch passes in one inning, excluding intentional walks, according to STATS.

"It looked like he was trying to be a little bit too fine in that second inning," Farrell said.

But if Pedroia hadn't botched a grounder moments later, the Red Sox would've gotten out of the inning trailing by only a run.

Iglesias hit a bouncer to second, and it appeared the inning would be over. Pedroia, however, couldn't field the ball cleanly and was relegated to making a short throw to second -- where Boston caught a break because shortstop Stephen Drew was off the bag when he took the toss.

The runner was called out anyway, but Iglesias beat Drew's relay to first as Peralta scored.

Torii Hunter followed with a two-run double, and Miguel Cabrera's RBI single gave the Tigers a five-run cushion in a game they needed to win to avoid being on the brink of elimination in Game 5.

"I think we probably contributed to the building of the inning, things we have control over, and that's hopefully command in the strike zone with a little bit more consistency. Jake has been so good at that -- uncharacteristic with the three walks inside of one inning," Farrell said. "You're asking for a little bit of trouble by additional baserunners, and unfortunately what turned out to be giving them an extra out lends to a crooked number on the board."

Boston banged out 12 hits but went 2 for 16 with runners in scoring position and stranded 10 overall. After overcoming a five-run deficit with the help of David Ortiz's tying grand slam in Game 2 at Fenway Park, the Red Sox were unable to rally this time.

"The one thing when we've been in stretches like this, we continually do a very good job of creating opportunities," Farrell said. "We did that tonight. We haven't done it so much in the first three games. But that's a tip of the hat to the pitching that we've been facing."

Jon Lester is scheduled to start Game 5 for Boston on Thursday night against Anibal Sanchez in a rematch of the series opener, won by the Tigers 1-0 at Fenway Park.

After that, the ALCS shifts back to Boston for at least one more game.

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